The ideal image ratio should be 3:2, for example, 660x440 pixel or 1500x1000 pixel. The file should be a jpg, png, or gif.
If the uploaded image ratio is within 20% of the 3:2 ratio, for example, 680x440, it will be cropped to the target ratio (660x440) to avoid gray bars on the sides.
If the image is not even close to the target ratio (e.g., more than 20% should be cropped), for example, 1200x440, no cropping will happen at all.
The maximum listing image file size is 16 MB.
What tool to use to resize and crop images
You can use a basic image editor (like Paint) or some online tools like Cropp.me or Cut My Pic.